1. Field of the Invention
The invention relates to photographic cameras having shutter mechanisms of the sliding blade-type and, more particularly, to cameras wherein the activation of an electrically-fired flash device is synchronized with movement of one of the shutter blades.
2. Description of the Prior Art
Shutter mechanisms of the sliding blade-type wherein the length of an exposure is determined by linearly guided shutter members are well known to the art. For example, U.S. Pat. No. 3,200,723, entitled "Shutter Timing Apparatus", discloses a shutter mechanism of this type which employs two blades. The first blade moves from a light blocking to a light unblocking position to initiate an exposure while the second blade moves from a light unblocking position to a light blocking position to terminate the exposure. Another shutter mechanism of the sliding blade-type which is well known in the art uses the continuous movement of a single shutter blade from a first light blocking position, through a light unblocking position, to a second light blocking position. A second or cover blade is provided to prevent the entry of light into the camera during recocking of the first shutter blade.
Many different types of devices are also known for synchronizing the actuation of a flash device with the movement of a shutter blade. For example, U.S. Pat. No. 2,960,922, entitled "Flash Synchronizing Device for Cameras"--discloses the use of a conductive first shutter element or opening blade to activate a flash firing circuit. As the opening blade moves from its light blocking position to its light unblocking position, a portion of the blade contacts a resilient conducting member thereby completing the flash firing circuit. Movement of a second shutter element or closing blade, from a light unblocking position to a light blocking position, breaks the contact between the first blade and the resilient conducting member by forcing the resilient conducting member away from the first shutter element. During recocking of the shutter mechanism, the second shutter element keeps the resilient conducting member separated from the first shutter element until the first shutter element can no longer contact the resilient conducting member.
The problem with the above described prior art flash synchronization devices is that the contacts remain closed longer than necessary and thereby unnecessarily load the power supply if the flash device happens to drain power after flashing.